1. Field of the Invention
This invention relates to a process for preparing color photographic light-sensitive materials.
2. Description of the Prior Art
Various compounds are known as a light-sensitive ingredient for color photographic light-sensitive materials. Of these, silver halide is commonly used. Silver halide color photographic light-sensitive materials commonly comprise a support having provided thereon a red-sensitive silver halide emulsion, a green-sensitive silver halide emulsion and a blue-sensitive silver halide emulsion, and possess various forms. There are known many techniques including, for example, a mixed grain process, a multi-layered light-sensitive material, a color diffusion transfer process, a silver-dye bleaching color photographic process, etc.
In the color photographic art, as photographic additives used for such silver halide color photographic light-sensitive materials, those of the type which are oil soluble to improve some properties, and are used by dissolving them in a substantially water insoluble, high boiling point solvent (e.g., a high boiling point organic solvent) and dispersing in a hydrophilic colloid aqueous solution (usually using an anionic surface active agent as an emulsifying agent) have recently come into wide use.
There are many such oil soluble photographic additives such as oil soluble couplers, oil soluble ultraviolet ray absorbing agents, oil soluble anti-fading agents, oil soluble color mixing preventing agents, oil soluble stain preventing agents, oil soluble anti-oxidants, etc.
As processes for emulsifying and dispersing these oil soluble photographic additives, there are known, for example, the following: U.S. Pat. Nos. 2,739,888, 3,352,681, etc., give descriptions as to ultraviolet ray absorbing agents, and U.S. Pat. Nos. 2,360,290, 2,728,659 3,700,453; etc., describe diffusion resistant alkylhydroquinones for use in preventing color fogging, color stain, color mixing, and the like. In particular, a process of emulsifying and dispersing oil soluble photographic additives using an anionic surface active agent as an emulsifying agent is known. For example, U.S. Pat. No. 2,332,027 describes a process using Gardinol WA (trade name of sulfonated cocoanut fatty alcohol, manufactured by E. I. Du Pont de Nemours and Co.) and triisopropylnaphthalenesulfonic acid salt, Japanese Pat. No. 428,191 describes a process using a water soluble coupler having a sulfonic group or carboxyl group and a long chain aliphatic group in combination as an emulsifying agent, and U.S. Pat. No. 3,676,141 describes a process using an anionic surface active agent having a sulfo group and an anhydrohexylester type nonionic surface active agent in combination. However, these emulsifying and dispersing processes provide dispersed particles of a coarse size (more than about 2.mu.) and fail to provide fine particles (less than about 0.5.mu.) required in recent photographic materials. In particular, the photographic element of a color photographic light-sensitive material coated on a support is designed to be thick, and, hence, when an emulsion dispersion to be added thereto contains coarse particles, light transmitting through the photographic element is scattered, which exerts a detrimental influence on photographic properties, making the element opaque. Also, it can be a factor in deteriorating image properties such as image sharpness and graininess.
On the other hand, decreasing the size of, in particular, a coupler emulsion dispersion increases the surface area of the particles per unit weight, which serves to increase coloring velocity, coloring efficiency, the covering power of formed dye images, and image density. However, in order to make the particle size of an emulsion dispersion finer, it is usually necessary to use an emulsifying agent in a large amount. The use of an emulsifying agent in a large amount is liable to cause coating troubles due to foaming of the emulsion, such as the formation of pinholes, uneveness in the coated film thickness, etc., and to deteriorate the film quality of the coated photographic element of a light-sensitive material (for example, the adhesiveness or the stickiness of the coated film becomes so large at high temperature and under high humidity that adhesion troubles between photographic light-sensitive materials or between photographic light-sensitive materials and a camera often result). Further, it inhibits the antistatic ability of an antistatic agent used in combination therewith. Still further, reducing the size of dispersed particles in an emulsion dispersion usually leads to agglomeration of the particles, destruction of the emulsion, etc., with the passage of time.
Thus, conventionally used surface active agents as described above fail to provide an adequate reduction in the particle size of an emulsion dispersion or entail some defects.